1. Field of Use
This invention relates generally to self-propelled steerable apparatus for removing material from the surface of a confined area and for pumping it to another location for disposition.
In particular, it relates to such apparatus which is especially well-adapted, for example, to clean sludge from the bottom of large liquid storage tanks, such as chemical or oil tanks, but could have other applications, such as cleaning any container or confined area having a solid rigid bottom or floor made of metal, concrete, plastic or the like.
2. Description of the Prior Art
My U.S. Pat. No. 5,093,949, issued Mar. 10, 1992, discloses self-propelled steerable sludge cleaning apparatus for cleaning sludge from the bottom of large liquid storage tanks. That apparatus, which had motor-driven crawler tracks and was able to move across the bottom of the tank along desired paths in accordance with a computer program, employed a horizontally disposed rotatable motor-driven auger for delivering sludge through a horizontal center-feed pipe to a motor-driven pump for subsequent disposal elsewhere. The auger had oppositely-wound helical auger flights at opposite ends and fed the sludge to the center-feed pipe located near the center of the auger. The motor-driven crawler tracks and associated components were relatively large and heavy and required a separate drive motor and associated controls to effect propulsion and steering.
My U.S. Pat. No. 4,574,501, issued Mar. 11, 1986, discloses underwater dredging apparatus of the crater sink type for dredging fluid material such as sand from an underwater area. That apparatus, which was stationary and positioned at a fixed location beneath a body of water by means of a crane, employed a horizontally disposed rotatable motor-driven auger for delivering sand through a vertical pipe to a motor-driven pump for subsequent disposal elsewhere. The auger had oppositely-wound helical auger flights at opposite ends and the vertical pipe was located near the center of the auger. That apparatus was incapable of self-propulsion to other locations.
Each of my prior art machines is well-adapted for its intended purpose but it is desirable to provide an improved apparatus for removing material from a confined area and which employs a horizontally-disposed motor-driven auger for supplying material to a motor-driven pump, such improved apparatus being self-propelled, steerable, more compact and less complex than prior art apparatus.
Heretofore, it was common practice in tank cleaning operations to decant the liquid in the tank into another container, to de-gas the tank to remove noxious vapors, and admit men into the tank through an access opening, such as a man-way in the side of the tank, with buckets and shovels to remove the sludge or sediment accumulated at the bottom of the tank. However, safety requirements aimed at limiting the exposure of working personnel to noxious vapors and liquids contained the tank are becoming more restrictive and expensive as time goes on. Therefore, it is desirable to eliminate the need for personnel to enter the tank and to limit the time clean-up personnel are exposed to the atmosphere within the tank while installing or removing automated cleaning equipment in the tank.
Furthermore, the need to decant the tank to be cleaned, as mentioned above, means that the tank must be taken out of service and this has very expensive consequences. For example, the liquid must be placed in another compatible container and tanks are very expensive. Furthermore, the tank to be cleaned is taken out of service and this is another expense. Also, an out-of-service tank could slow down or even stop an industrial process, resulting in a very expensive production cut-back.